The present invention relates to a lead terminal for electronic component, and a ceramic resonator and a train of electronic components using the lead terminals.
With the tendency to pursuit of reduction in size, increase in grade and increase in number of functions of electronic appliances, miniaturization of electronic components used in the electronic appliances has been advanced and accuracy of the order of tens of microns has been demanded as accuracy of assembling position in an assembling process. This demand is applied to assembling of lead terminals of an electronic component without exception. Particularly in the case of lead terminals having a structure in which end edges of an electronic component device shaped like a board are inserted into U-grooves of the terminals so that opposite ends of the electronic component device are held by the terminals, high accuracy of position in attachment of the terminals in depthwise directions of the U-grooves can be obtained because of the structure of the terminals, but accuracy of position in attachment of the terminals in lengthwise directions of the U-grooves is apt to vary according to divergence in positional adjustment of an inserting machine, positional displacement of the terminals, or the like.
For example, a ceramic resonator disclosed in Patent Document 1 is an example of this type electronic component using the terminals. The ceramic resonator has a structure in which first and second vibrating electrodes are formed on opposite surfaces (in a direction of thickness) of a piezoelectric substrate made of a ceramic substance and an electrically insulating resin layer is deposited on each surface (in the direction of thickness) of the piezoelectric substrate so that cavities are formed around the first and second vibrating electrodes respectively to prevent the resin layer from blocking vibration.
Each of the first and second vibrating electrodes has first and second lead electrodes. The respective first and second electrodes of the first and second vibrating electrodes are led out to opposite sides of the piezoelectric substrate laterally. First and second lead wires are attached to the laterally opposite sides of the piezoelectric substrate and connected to the first and second lead electrodes respectively by means of soldering or the like. The whole of the resulting piezoelectric substrate is coated with an external resin. In this manner, a finished product is obtained.
Each of the first and second lead wires has two side plates facing each other with a distance. The side plates are formed so that one end of one side plate is continued to one end of the other side plate while the other end of one side plate and the other end of the other side plate form open end edges. Accordingly, a U-groove is formed between the two side plates of each of the first and second lead wires, so that opposite sides of the piezoelectric substrate can be inserted into the U-grooves respectively. The first and second lead wires between which the piezoelectric substrate is held are positioned while protrusive ends of the open end edges of the two side plates of each lead wire are brought into contact with an outer circumferential surface of the electrically insulating resin layer.
The ceramic resonator, however, has no means for positioning the first and second lead wires in the vertical direction of the piezoelectric substrate corresponding to the lengthwise direction of the U-grooves. For this reason, when positional displacement in the direction of insertion of the piezoelectric substrate is caused by divergence in positional adjustment of a piezoelectric substrate inserting machine, positional displacement of terminals, etc., the displacement may directly result in positional displacement in the vertical direction of the piezoelectric substrate.
The positional displacement has influence on subsequent processes, so that characteristic failure may be generated or variation in characteristic or deterioration of the yield may be caused because the piezoelectric characteristic is suppressed. In addition, positional variation in the vertical direction of the piezoelectric substrate induces coating unevenness in the external resin coating process, so that the amount of the external resin varies in a neighbor of the terminal base of each of the first and second lead wires.
[Patent Document 1] JP-A-2002-13637